1. The human circulatory system This system is one of the most important in the body. It is made up of 3 main parts: The heart The Lungs The blood vessels. This system is also known as the cardiovascular system.

2. The human circulatory system Heart Lungs Heart Body Blood pumping

3. The human circulatory system Heart Lungs Heart Body Blood pumping The heart pumps blood to the lungs

4. The human circulatory system Heart Lungs Heart Body Blood pumping The lungs remove the carbon dioxide from the blood and refill it with oxygen.

5. The human circulatory system Heart Lungs Heart Body Blood pumping The heart then pumps the blood around the body.

6. The human circulatory system Heart Lungs Heart Body Blood pumping The blood is transported all around the body, where oxygen is taken and replaced with carbon dioxide.

7. The human circulatory system Heart Lungs Heart Body Blood pumping The blood is cleaned in the kidneys to remove all the waste before it returns to the heart.

8. The human circulatory system Heart Lungs Heart Body Blood pumping The cycle starts again

9. The human circulatory system The blood vessels run throughout the body supplying oxygen to every cell in the body. They are made up of 3 types – arteries, veins and capillaries.

10. The human circulatory system Arteries are thick blood vessels that you can easily feel in the form of a pulse. They transport oxygenated blood to the cells. As they are full of oxygen, they appear to be a deep red colour.

11. The human circulatory system Veins are thick blood vessels. They transport blood back to the heart from the cells. As they have little oxygen, they appear to be more a blue colour than red.

12. The human circulatory system Capillaries are thin blood vessels. They allow oxygen and nutrients to pass to the cells, and waste products and carbon dioxide to be removed from them. They are small to allow them to reach every cell in the body.